System and method for adjusting carbon dioxide concentration in indoor atmospheres

Abstract

An electrochemical device suited to modifying a carbon dioxide concentration in an interior space includes a cathode chamber with an inlet which receives a feed gas containing carbon dioxide. A reduction catalyst layer in the cathode chamber reduces carbon dioxide in the gas to form an ionic carrier species. An anode chamber with an outlet outputs a gas comprising carbon dioxide. A solid electrolyte membrane spaces the anode chamber from the cathode chamber and transports the ionic carrier species between the cathode chamber and the anode chamber. The membrane includes an ionic liquid. An oxidation catalyst layer in the anode chamber oxidizes the ionic carrier species to form carbon dioxide. A voltage source provides a voltage difference across the membrane.

Description

[0001]This application claims the priority of U.S. Provisional Application No. 62 / 468,350, filed Mar. 7, 2017, and U.S. Provisional Application No. 62 / 468,332, filed Mar. 7, 2017, both entitled SYSTEM AND METHOD FOR EFFECTIVELY REMOVING INDOOR CO2, by Vedharathinam, et al., the disclosures of which are incorporated herein in their entireties.BACKGROUND[0002]The exemplary embodiment relates to regulation of carbon dioxide concentrations in the atmosphere of an enclosed space. It finds particular application in connection with an apparatus and method for reducing carbon dioxide from indoor air.[0003]Various methods have been used to adjust the carbon concentration in indoor air. In commercial buildings, frequent ventilation using outdoor air (generally 300-400 ppm carbon dioxide, or less) is often used to ensure that indoor air is maintained at ASHRAE-recommended levels (ASHRAE Standard, Ventilation for Indoor Air Quality, 2003). The cost of ventilation can be quite high. For example,...

AI Technical Summary

Benefits of technology

The patent describes a device that removes carbon dioxide from the air using an electrochemical process. The device can either reduce the partial pressure of carbon dioxide in the air or increase it depending on the desired needs. This can be useful in various applications such as air purification or carbon dioxide pumping for industrial processes.

Problems solved by technology

The cost of ventilation can be quite high.

This corresponds to a high energy cost for what is largely building CO2 removal (about 2.2 MJ mol−1 CO2).

In the absence of intelligent CO2 removal systems, a significant amount of energy is wasted in excessive ventilation to dilute indoor air to acceptable CO2 levels (Mysen, et al., “Occupancy density and benefits of demand-controlled ventilation in Norwegian primary schools,” Energy & Buildings, 37, 1234-1240 (2005)).

Given that research now points to the benefits of more stringent air quality standards (below 650 ppm) for occupant productivity, the energy-expensive use of ventilation is expected to increase.

The amount of CO2 removal is dependent on the absorbent volume, thus tending to make the system heavy.

This limits the ability to provide continuous processing of indoor air and also generates a large amount of heat.

Live plants can also provide some indoor CO2 removal, but the ratio of plants to occupants needs to be high, and maintaining healthy plants indoors can be expensive (Darlington, et al., “The biofiltration of indoor air: implications for air quality,” Indoor Air, 10 (1): 39-46 (2000))

The carrier, however, has a relatively poor oxygen stability and has demonstrated only low CO2 removal flux.

However, the process requires a high reduction potential (−3 V vs Ag|AgCl) and cannot operate continuously.

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